The main focus of our research is to use fluorescence spectroscopy and microscopy in conjunction with detailed chemical and cytological analyses in order to characterize the cell surface membrane complex. Particular effort will be devoted to attempts to corroborate and refine the hypothesis on surface modulating assemblies, and to define their chemical components and biological functions. These studies will involve the chemical characterization of macromolecules by various methods including fluorescence spectroscopy, application of fluorescent probes to the analysis of the dynamics and interactions of macromolecular assemblies, and the development of instrumentation and techniques for quantitative fluorescence microscopy. BIBLIOGRAPHIC REFERENCES: Schlessinger, J., Elson, E.L., Webb, W.W., Yahara, I., Rutishauser, U., and Edelman, G.M. Receptor Diffusion on cell surfaces modulated by locally bound concanavalin A. Proc. Nat. Acad. Sci. USA 74, 1110-1114 (1977). McClain, D.A., D'Eustachio, P., and Edelman, G.M. Role of surface modulating assemblies in growth control of normal and transformed fibroblasts. Proc. Nat. Acad. Sci. USA 74, 666-670 (1977).